This proposal describes plans for a study of the clinical features of human immunodeficiency virus (HIV) dementia. To assess the impact of HIV-related neurological and neuropsychological changes on quality of life, activities of daily living, and work disability, as endpoints of immediate concern to patients infected with HIV. To measure disease progression in all subjects participating in the study by examining progression of disease from baseline to significant endpoints, i.e. death or loss of independence in daily living.